For the newborns, neonatal jaundice is the common disease [1]. There are two types of neonatal jaundice: one is physiological and the other is pathological. As for the physiological, it can be automatically recovered without any treatments. Whereas, for the pathological, it falls into three types: mild, moderate and severe. If they were not to be properly or promptly handled (esp. the severe one), it can cause kernicterus, and consequently sequela or even death may occur [2]. The pathogeny of neonatal jaundice [2] is that the amount of bilirubin overproduces so that it is beyond the excretive and metabolic capability of the neonatal body, thus results in the accumulation of redundant bilirubin. Therefore, the treatment should be based on how to reduce the level of bilirubin effectively and quickly. Now, three clinical thera-pies [3-5] (drug, blue phototherapy and exchange trans-fusion) are in use for the treatment. Drug can accelerate the excretive and metabolic process of bilirubin; however, it is now seldom used in clinic due to its great side effect [6]. Blue phototherapy can change the excretive and metabolic pathway of bilirubin, which is only suitable for mild sick neonatal but also has side effect [7-8]. Exchange transfusion is now the last resort for the treatment of severe neonatal jaundice, in which there are some disadvantages, such as blood cross-infection, scarcity of blood source and operation complexity [9-10]. Because the incidence of severe neonatal jaundice is in rise [1,11] and there exist some larvaceous disadvantages to be overcome for the exchange transfusion, in view of high safety, there is an imminent demand to develop a new, safer, more economic and simple treatment for severe neonatal jaundice to substitute exchange transfusion.

Hemoperfusion [4,12-13] has been clinically used since 1970s, whose characteristics are to clear pathogenic material directly and quickly from blood or plasma so as to purify the blood, and whose key depends on the perfusion adsorbent with high specificity and adsorption as well as good hemocompatibility [14-16]. Therefore, hemoperfusion has the potentiality to substitute exchange transfusion for the treatment of severe neonatal jaundice. Because of the newborn physiological particularity, the key to apply the hemoperfusion for the treatment depends on whether the bilirubin adsorbent is of high specificity, high adsorption and good hemocompatibility for the newborn blood. Now, several bilirubin adsorbents have been reported, such as NKA-9 [17], NK-110 [17], PVA [17], PMMA [18], chitosan [19] and burning resin [20], which are mainly used in industry to extract bilirubin or in clinic for adult hyperbilirubinemia hemoperfusion [21]. But within our knowledge, there is no report about their use in the hemoperfusion for severe neonatal jaundice and on their adsorption for bilirubin from severe neonatal jaundice plasma/blood. This study was aimed to test their adsorption properties upon neonatal jaundice plasma, and then screen out the best for further evaluation, with an aim to provide clinical experimental reference for the choice or development of bilirubin adsorbent for the hemoperfusion in severe neonatal jaundice.

According to the structure of bilirubin, the materials [17-20] currently reported to have better adsorption for bilirubin are mainly NKA-9, NK-110, PMMA, PVA, chitosan and burning resin. NKA-9 is a kind of macroporous resin with cyano, which has been mainly used in industry to extract bilirubin due to its good affinity to bilirubin; NK-110 is a kind of macroporous resin, which has been reported for the treatment of adult hyperbilirubinemia perfusion due to its good affinity to macromolecules toxic substances; PMMA also has adsorption for bilirubin, as well as good biocompatibility and blood compatibility, which has been widely used in biomedical materials field;PVA has been widely used in enzyme immobilization and blood purification fields in the form of membrane or water gel;Polysaccharide is a newly-developing adsorption and separation materials;Burning resin is an adsorption material from a variety of polymer resin produced by high-temperature carbonization.

This preliminary evaluation indicated the level of TB and DB in the severe neonatal jaundice plasma was significantly reduced after the plasma was hemoperfused by the six kinds of bilirubin adsorbing materials respectively, DB is a more important medical indicator for it reflects the function of liver. Among them, the adsorption of NKA-9 and PVA was the most significant; the adsorption ratio of NKA-9 was over 75%, and the adsorption ratio of PVA was over 50%. Although the level of TB and DB did not reduce to the normal level, the level had been below the threshold value of pathological neonatal jaundice (204-255µmol/L), which can help the doctors and the patients buy time to create favorable conditions for other treatments of neonatal jaundice. Regarding to the aspect of blood compatibility, NKA-9 resin did not cause significant effects on most of blood components indicators of newborn, and those indicators were also in line with the clinical reference value [20-21]. Inevitably, some indicators had significant change. For example, the level of HCO_3- was below the normal value, which is adverse and unexpected in clinic treatment. However, such disadvantages can be easily remedied by other means. NKA-9 had major effects on the enzymatic system indicators of newborn, which is unexpected and need proper remedy. NKA-9 had little effects on the hemolytic system and blood clotting system indicators of newborn, which is favorable. Current studies [15,22] indicate hemoperfusion therapy for severe hepatitis is a good method for clearing bilirubin quickly. Due to hyperbilirubinemia becoming a common problem, therefore bilirubin adsorption therapy has great applicable prospect. In American, about 60% of 40 million neonatal may develop hyperbilirubina-emia [23], whereas 60% of hyperbilirubinaemia neonatal patients may develop into jaundice, of which pathological jaundice is higher than physiological one, whereas in China, incidence of pathological jaundice of newborn is up to 38.4% [24]. Because there still exist some drawbacks in current clinical therapies for pathological neonatal jaundice, improvements or new therapy is in urgent demand in order to gain great safety, therefore, how to cure neonatal jaundice (esp. the severe) with perfusion therapy and develop more effective, secure and economic bilirubin adsorbing material should be a novel challenge to the medical staff and scientists, and also has extensive market prospect. Unfortunately, the in vivo study cannot be now done because of the limitations of current technology.

The preliminary evaluations offer us the knowledge and reference of hemoperfusion being potentially applied in the treatment of severe neonatal jaundice; however, there still exists some problems to be resolved before it can be clinically used. Among six kinds of bilirubin adsorbing material candidates, NKA-9 resin had best adsorption for bilirubin from severe neonatal jaundice plasma, which may be expected as the adsorbing material to be used for the clinical hemoperfusion of neonatal jaundice disease with proper modification and therapeutic alliance. In future studies, people should develop new adsorbing material with high adsorption for bilirubin and with no/minor influences on other medical indicators except TB/DB, and/or seek compensative measurements to overcome the disadvantages causing by current bilirubin adsorbing materials.